The present invention relates to cellular and satellite communications. More particularly, the invention relates to a method and a system for implementing terminal to terminal connections via a geosynchronous earth orbit satellite in a satellite communication network.
Background and Description of Related Art
A mobile satellite communication system such as the Geosynchronous Earth Orbit Mobile (GEM) network discussed herein, typically includes one or more satellites, at least one fixed ground terminal such as a gateway system (GS) and several mobile access terminals (ATs). The access terminals typically communicate with the public switched telephone network (PSTN) or other mobile terminals via an air communication interface between the satellite and the gateway. Using the mobile access terminals, the satellite system provides a variety of telephony services. Satellite telephony systems as described herein share call processing information with terrestrial systems such as the GSM cellular system to allow compatibility between the satellite, cellular, and the public switch telephone network services. The terrestrial standards such as GSM may not apply directly to the mobile satellite communication system, more particularly the satellite air interface poses physical constraints not accounted for in the GSM architecture.
A number of communication systems utilizing satellites and small mobile terminals provide voice and other information communication. In such systems, the single-hop one way propagation delay is about 270 ms. This is about at the limit of acceptability for most users. If a call is established between two such users with two satellite hops, the one way delay becomes approximately 540 ms, which is generally unacceptable. In order to reduce this propagation delay when two mobile users are conversing, it would be desirable to provide a link made to establish a connection through the satellite, such that the connection involves only a single satellite hop.
Thus, there exists a need for a method and a system for performing satellite switched communications to enable the GEM network to establish a single hop satellite link between two user access terminals.